<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .div {
            height: 20px;
            text-indent: 2em;
        }
    </style>
</head>

<body>

    <!-- div*5 -->
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <!-- ul>li父子级标签 -->
    <ul>
        <li></li>
    </ul>
    <!-- div+p同级标签 -->
    <div></div>
    <p></p>
    <!-- .demo -->
    <div class="demo"></div>
    <!-- #csc -->
    <div id="csc"></div>
    <!-- .demo$*5 -->
    <div class="demo1"></div>
    <div class="demo2"></div>
    <div class="demo3"></div>
    <div class="demo4"></div>
    <div class="demo5"></div>
    <!-- div{$}*5 -->
    <div>1</div>
    <div>2</div>
    <div>3</div>
    <div>4</div>
    <div>5</div>
</body>

</html>